Study Finds Beaver Dams Boost River Water Quality and Overcome Drought Impact

American beaver populations are thriving in the western United States as temperatures become hotter and dryer, according to a Stanford study. According to new research, their prolific dam building boosts river water quality so much that it overcomes the negative impact of climate-driven droughts.

Beavers, also known as nature’s engineers, were nearly driven to extinction by the fur trade, and today their population ranges from 6 to 12 million in the United States. When climate change degrades water quality and harms ecosystems, beaver dams may help mitigate the impact.

This is the finding of a new study published in Nature Communications on November 8 by Stanford University scientists and colleagues. Beaver dams have a significantly larger impact on quality in mountain watersheds than climate-driven, seasonal extremes in precipitation, according to the research. The wooden barriers elevate upstream water levels, channeling water into neighboring soils and tributary streams, creating a riparian zone. These zones operate as filters, removing extra nutrients and impurities before the water returns to the main river downstream.

Although hotter, drier weather brought on by climate change may degrade water quality, these same circumstances have also helped the American beaver thrive once more in the western United States, which has led to an increase in dam construction.

This study looked at the East River in the state of Colorado. In 2018, the water level was very low and in 2019 it was higher. They studied the water levels and the things in the water during these two years. They put special tools called pressure transducers in the river to measure the water level and took samples of the water. They also found that beavers built a dam in the river during the summer of 2018, when the water level was very low. The dam caused the water to rise in some places and stay low in others, which changed how the water moved through the area. The dam made a bigger difference in the water movement than even the big snowmelt floods that usually happen.

The study also discovered that a beaver dam helped remove a lot of nitrogen from the water. This is significant because too much nitrogen can degrade water quality. It can cause excessive algae growth, which is harmful to fish and other aquatic species. The beaver dam eliminated 44% more nitrogen than is normally eliminated during different seasons.

This study is significant because it demonstrates that natural changes, such as beaver dams, can help maintain our water clean. While we consider how the environment may change in the future as a result of factors such as climate change, we must also consider how nature may change. Our nation’s environment, which has lost a large portion of its wetlands to development and farmland, would greatly benefit from this comeback of nature’s engineers. Despite this, we frequently clash with beavers over who gets to occupy floodplains. 

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